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| mikepl
June 13, 2025, 12:47:00 GMT permalink Post: 11900477 |
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| EXDAC
June 15, 2025, 20:56:00 GMT permalink Post: 11902827 |
Edit to add - RIPS will likely maintain CVR function. |
| DaveReidUK
June 15, 2025, 21:05:00 GMT permalink Post: 11902840 |
But as previously posted a recorder is only as good as the systems that provide the data to it. If those systems, or some of those systems, are not powered the data is simply not available to be recorded. You need the DFDAU (or equivalent) to be powered and you need the systems that feed data to the DFDAU (or equivalent) to be powered and operational.
Edit to add - RIPS will likely maintain CVR function. |
| DIBO
June 16, 2025, 00:47:00 GMT permalink Post: 11903013 |
* only the forward EAFR (Enhanced airborne flight recorder) has an (external) RIPS (Recorder independent power supply) * and this RIPS provides, in addition to the forward EAFR, the cockpit area microphone and the preamplifier for this microphone with 10 minutes of backup power Pretty recently, Indian media was reporting that the forward "CVR" has been recovered. Pure speculation..but one might interpret the use of this incorrect terminology and the continued search for this second 'black box' while the rear EAFR should have been easily recovered from the mostly intact tail-section, as an indication that things aren't going as well as expected regarding FDR/CVR data-extracting (as in rear EAFR lacking the last x crucial seconds, and forward EAFR now essential for recovery of the last x-seconds of area-CVR recordings, thanks to RIPS) |
| DIBO
June 16, 2025, 00:47:00 GMT permalink Post: 11903732 |
* only the forward EAFR (Enhanced airborne flight recorder) has an (external) RIPS (Recorder independent power supply) * and this RIPS provides, in addition to the forward EAFR, the cockpit area microphone and the preamplifier for this microphone with 10 minutes of backup power Pretty recently, Indian media was reporting that the forward "CVR" has been recovered. Pure speculation..but one might interpret the use of this incorrect terminology and the continued search for this second 'black box' while the rear EAFR should have been easily recovered from the mostly intact tail-section, as an indication that things aren't going as well as expected regarding FDR/CVR data-extracting (as in rear EAFR lacking the last x crucial seconds, and forward EAFR now essential for recovery of the last x-seconds of area-CVR recordings, thanks to RIPS) |
| DIBO
June 16, 2025, 23:16:00 GMT permalink Post: 11903863 |
* only the forward EAFR (Enhanced airborne flight recorder) has an (external) RIPS (Recorder independent power supply)
* and this RIPS provides, in addition to the forward EAFR, the cockpit area microphone and the preamplifier for this microphone with 10 minutes of backup power |
| DaveReidUK
June 17, 2025, 21:29:00 GMT permalink Post: 11904679 |
the difference may lay in the content that was recorded and not so much the 2 identical EAFR's. Only the forward EAFR is connected to a dedicated backup battery (RIPS) which also provides backup power to the Cockpit Area Microphone. So in case of a major electrical power mishap, the forward - and likely (externally?) damaged - EAFR might be crucial for recovering all available CVRecordings. Hence the somewhat understandable split-up in news-reports, between FDR data (from the rear EAFR) and complete CVR recordings (from the forward).
If the aft EAFR ceased recording at the point (just short of the runway end) where the ADS-B and likely everything else went dark, then the extra 30 seconds of CVR recording from the forward recorder could well be crucial to the investigation. |
| Gary Brown
June 19, 2025, 09:20:00 GMT permalink Post: 11905856 |
https://www.geaerospace.com/sites/de...rder-3254F.pdf The rear EAFR doesn't have power backup. So it will only record data (both CVR and FDR) while it has normal electrical power. At what point before impact that power was lost, we do not know. |
| Kraftstoffvondesibel
June 20, 2025, 16:36:00 GMT permalink Post: 11907117 |
Regarding the Recorders, obviously nothing to do with the cause, but still:
Given:
"The forward installed EAFR along with theCockpit Area Microphone and Preamplifier are typically connected to the Recorder Independent Power Supply (RIPS), providing a backup power source for 10 minutes in the event of power interruptions."
1/in the tail, likely to not be overly damaged, but might have stopped being powered at the moment the thrust was lost. Due to digital delay, it might not have catched interesting transient data of the cause. It is too far removed from the cockpit to have independent analog feeds from microphones or other equipment. 2/ The one in the front, much more likely to have been damaged, and also more likely to be useful because it had an independent area microphone cockpit source. I have 2 questions and a speculation: Speculation: The front recorder also lost all data because the systems powered down, except it independently, and by analog direct means, powers the cockpit area microphone w/micpre and could continue recording that for a good amount of time on a small battery. This then might be the recorder recieving special treatment and delayed read out, because of the damage, and because it contains audio from the cockpit, (while the other one, might already have been read by conventional means, but doesn't contain anything of use because this was a sudden event and digital latency. Or as I assume some might speculate, the tail recoder hinted to information leaving the decision on whether to read the front recorder abroad to someone much higher up) Questions: 1/Would the recorders lose access to aircraft data streams when engine power is lost, at least temporarely making the cockpit area mic recorded by battery power on the front recorder the only source of information ? 2/The recorders only draw 20W, why is it the front have reserves only for 10 minutes? Can you even buy a battery that small giving 28VDC? Why is such a limited solution selected? (And since they have a microphone input, and the units are interchangeable why don't they just stick a few grams worth of microphone in the back of the aircraft as well, just to catch mechanical noises that could help when data input is missing. Audio sensors seems underrated.) ( For reference, This battery could power the whole recorder for an hour: https://www.batteryspace.com/custom-nimh-battery-28-8v-800mah-23wh-with-tabs.aspx ) Last edited by T28B; 20th June 2025 at 18:25 . Reason: formatting |
| ignorantAndroid
June 21, 2025, 02:03:00 GMT permalink Post: 11907444 |
The 10-minute limit has nothing to do with the battery capacity. It's to prevent the recorder from continuing to operate after an accident and thus overwriting the audio of interest. There's a timer in the RIPS module. It will stop providing power after exactly 10 minutes, regardless of state of charge. Last edited by ignorantAndroid; 21st June 2025 at 02:58 . Reason: spelling |
| Recidivist
June 21, 2025, 05:36:00 GMT permalink Post: 11907498 |
It is a battery, not a supercapacitor. Most commonly nickel-cadmium, because that chemistry has been used in aircraft for decades. They're safe and readily accepted by regulators. Li-ion can be used, but a "special condition" from the regulators is needed, plus the weight savings would be negligible.
The 10-minute limit has nothing to do with the battery capacity. It's to prevent the recorder from continuing to operate after an accident and thus overwriting the audio of interest. There's a timer in the RIPS module. It will stop providing power after exactly 10 minutes, regardless of state of charge. ignorantAndroid yours is a good and helpful explanation, thank you. Can you please advise what is the trigger that starts the 10 minute period? I guess I mean, what signal tells the battery to stop supplying power 10 minutes from "now". Thanks |
| EDML
June 21, 2025, 11:52:00 GMT permalink Post: 11907686 |
It is a battery, not a supercapacitor. Most commonly nickel-cadmium, because that chemistry has been used in aircraft for decades. They're safe and readily accepted by regulators. Li-ion can be used, but a "special condition" from the regulators is needed, plus the weight savings would be negligible.
The 10-minute limit has nothing to do with the battery capacity. It's to prevent the recorder from continuing to operate after an accident and thus overwriting the audio of interest. There's a timer in the RIPS module. It will stop providing power after exactly 10 minutes, regardless of state of charge. https://www.geaerospace.com/sites/de...rder-3254F.pdf |
| ignorantAndroid
June 21, 2025, 17:00:00 GMT permalink Post: 11907903 |
SLF here, but former electronics tech in coms/navaids in civil aviation.
ignorantAndroid yours is a good and helpful explanation, thank you. Can you please advise what is the trigger that starts the 10 minute period? I guess I mean, what signal tells the battery to stop supplying power 10 minutes from "now". Thanks |
| OPENDOOR
June 21, 2025, 18:11:00 GMT permalink Post: 11907957 |
It consumes 20.5 watts so a ten minute power supply should not only be easy to integrate but also already exists and is certificated for the forward mounted unit. |
| Musician
June 22, 2025, 10:34:00 GMT permalink Post: 11908427 |
The Jeju recorders were okay if I recall correctly, they just had no input, was that the case?
Last edited by Musician; 22nd June 2025 at 11:12 . |
| OPENDOOR
June 22, 2025, 14:57:00 GMT permalink Post: 11908601 |
Enhanced Airborne Flight Recorders (EAFR)
Whilst we wait for any announcements from the crash investigators can anybody suggest the logic behind providing the front mounted Enhanced Airborne Flight Recorders (EAFR) with a
Recorder Independent Power Supply (RIPS) but not giving the identical aft mounted EAFR unit the same protection where it is less likely to suffer damage?
The RIPS unit is a certificated device that just has to supply 20.5 watts for ten minutes so cost cannot be a consideration. Another debate that should now be had is real time telemetry. Given the number of airlines contracting with Starlink for internet services onboard their fleets uploading the data stream fed to FDR's wouldn't put a dent on the available bandwidth and the search and recovery process for FDR's would be a thing of the past. |
| quentinc
June 22, 2025, 15:21:00 GMT permalink Post: 11908618 |
Whilst we wait for any announcements from the crash investigators can anybody suggest the logic behind providing the front mounted Enhanced Airborne Flight Recorders (EAFR) with a
Recorder Independent Power Supply (RIPS) but not giving the identical aft mounted EAFR unit the same protection where it is less likely to suffer damage?
The RIPS unit is a certificated device that just has to supply 20.5 watts for ten minutes so cost cannot be a consideration. Another debate that should now be had is real time telemetry. Given the number of airlines contracting with Starlink for internet services onboard their fleets uploading the data stream fed to FDR's wouldn't put a dent on the available bandwidth and the search and recovery process for FDR's would be a thing of the past. |
| OPENDOOR
June 22, 2025, 15:40:00 GMT permalink Post: 11908632 |
If it has no power it won't record anything at all, like the fact that multiple electrical systems are U/S but as a limited power supply from the RAT or APU comes on-line it would have something to record. It seems to me absurd that it is not powered at all times.
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| Musician
June 22, 2025, 16:20:00 GMT permalink Post: 11908657 |
Whilst we wait for any announcements from the crash investigators can anybody suggest the logic behind providing the front mounted Enhanced Airborne Flight Recorders (EAFR) with a
Recorder Independent Power Supply (RIPS) but not giving the identical aft mounted EAFR unit the same protection where it is less likely to suffer damage?
Can you point to a single incident where this would have made a difference?
Another debate that should now be had is real time telemetry. Given the number of airlines contracting with Starlink for internet services onboard their fleets uploading the data stream fed to FDR's wouldn't put a dent on the available bandwidth and the search and recovery process for FDR's would be a thing of the past.
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| Semreh
June 22, 2025, 16:37:00 GMT permalink Post: 11908670 |
In reverse order, and the first one being very speculative: The type of battery will likely be highly specific for the usecase, here rugged before anything else. Likely specialized chemistry or one of those hybrid solid state ones. Commonly they trade capacity for other features.
Regarding the recording feature, there's three types of microphone commonly used nowadays: Condenser and Ribbon type are somewhat fragile and require power to record audio while Dynamic type is basically a reverse speaker and is considered rugged. There's an off chance that a Piezzo microphone would be used here as they are basically indestructible but usually reserved for recording while in contact with a large sound transducer. My guess based on that is that we're looking at a dynamic microphone with a run of the mill preamp. Depending on the actual electric setup this would yield a handful of different possible installations: 1) The "Cockpit Area Microphone" (hereby christened CAM because I like abbreviations) is a self contained unit consisting of a Microphone, a preamp and AD converter. This would mean while provided power the digital recording could be passed to either EAFR. 2) The CAM is a self contained unit consisting of a Microphone and a preamp. This would mean while provided power it could send an analog audio signal to the forward EAFR no problem, but would potentially struggle generating enough of a signal to be picked up by the rear EAFR. 3) The CAM is just a Microphone. This would mean it requires either no or very little power (even Condenser Mics usually require only Milliwatts) but the signal would be very hard to send over long distances and would require the EAFR to have a preamp. In general it is audio engineering 101 to place a preamp as close to the source as possible to avoid noise. Thus I would rule out 3. It has both ups and downs to convert the analog signal to a digital signal, and there is a possibility they'd do both. In either case I am confused from an audio engineering standpoint why the rear EAFR would not pickup audio from the CAM if the forward EAFR does. Unless the rear EAFR is fed (audio) data only via BUS, which would be an interesting choice. Also keep in mind that historically the CVR was also located in the tail section and very much received an analog signal over the entire distance. There's really no technical reason this wouldn't be possible, I routinely use far longer cables when running audio signals at concerts and those can't use compression because it would dumpster sound quality. So, yeah, I don't understand why there would be a mismatch between the recordings of either EAFR, unless there was something else preventing all signal transmission towards the rear EAFR. The CVR in the rear has been a thing for 80 years now. Regards, Justus My understanding is that, as you say, the CAM has a preamp. That preamp can be powered by the RIPS that accompanies the forward EAFR. In addition, I believe there is a single analogue connection from the CAM+preamp to the aft EAFR in addition to the analogue connection from the CAM+preamp to the forward EAFR. I believe, but am not sure,that the other flight-deck audio (headsets) is carried digitally over the fibre-optic network to the aft EAFR. The network may or may not be in operation in the event of an electrical failure: I simply don't know. The publicly available information I can find is not stunningly clear about this. AEROSAFETY WORLD, January 2008 - https://flightsafety.org/asw/jan08/a...47-48.pdf?dl=1
In the 787, the EAFRs store within their CVR-function memory partitions two hours of data from four audio channels and all data link messages. \x93The CVR function receives audio from three digital audio crew channels provided by the flight deck audio system and one analog audio channel from the cockpit area microphone and preamplifier,\x94 Elliott said.( Jim Elliott, a systems/applications engineer for the manufacturer. )
The Cockpit Voice Recorder function records the flight deck communications between crew members and also captures the general acoustical sound environment of the flight deck. The CVR function receives three analog audio crew channels provided by the Flight Deck Audio System and one analog audio channel from the cockpit Area Microphone and Preamplifier (AMP). The cockpit area audio and the three audio crew channels are recorded in both the forward and the aft installed EAFR recorders. The CVR recording duration is two hours minimum. Recorded audio can only be downloaded when the EAFR is off the aircraft.
https://data.ntsb.gov/Docket/Documen...ort-Master.PDF
Two EAFRs are installed on Boeing 787 aircraft, one forward and one aft. The forward and aft recorders are powered by the left and right 28V DC buses respectively. The forward recorder is equipped with a recorder independent power supply (RIPS) to provide backup power to the recorder for approximately 10 minutes once left DC bus power is lost. Both recorders record the same set of flight data independent of each other.
What I have been unable to determine is whether the right and/or left 28 V DC buses are powered from the main battery in case of failure of the AC power supply. To my untrained eye, it looks like the Captain's flight displays are powered from the main battery in extremis (28 V DC - C1), but that there are various circuit breakers, that could be automated, that may or may not allow or prevent other loads (such as the F/O's flight displays (28 V DC - C2), or the aft EAFR, being supplied by the main battery, (See link to diagram). There could well be very drastic automated load shedding. https://kb.skyhightex.com/wp-content...l-1024x640.png If the right 28 V DC bus was unpowered for any period, it follows that the aft EAFR was not recording for that period. This would make the forward EAFR important in case of a power failure that prevented the right 28 V DC bus from providing power. All the information that is unclear to me will be transparently clear to the crash investigators. But it seems to me that the aft EAFR will not hold data for any period that the right 28 V DC bus is not operating. Whether that applies to this incident is an open question. |